There has been conventionally known a tire which includes at least one belt reinforcing layer disposed on the outer circumferential side of the crown region of a carcass which may be radially configured, the belt reinforcing layer being formed of, for example, a cord extending at an angle of 5° or less relative to the tread circumferential direction so as to extend substantially in the tread circumferential direction, to thereby suppress the radial growth of the tire by the belt reinforcing layer.
One of the examples of the aforementioned tire includes a pneumatic tire provided with: a pair of bead cores; a toroidal carcass layer disposed between the pair of bead cores; a circumferential belt layer disposed on the outside of the carcass layer in the tire radial direction; and an inner inclined belt layer and an outer inclined belt layer disposed on the outside of the circumferential belt layer in the tire radial direction (see Patent Literature 1).
Meanwhile, in recent years, along with the increase of low-profile wide tires, it is indispensable to provide a circumferential belt layer as a belt reinforcing layer in view of maintaining the tire shape when filled to an internal pressure.
Further, tires are required to have high durability, in consideration of the yearly increasing load to which the tires are to be subjected.
Further, in the case of a pneumatic tire to be mounted onto a steering shaft, the tire is likely to be subjected partial wear caused in the shoulder end side of the tread by side force (SF) generated due to a slip angle imparted thereto. In view of this, the tire is designed to have a smaller tread width for the purpose of reducing the wear volume, to thereby suppress the partial wear. In a tire with a reduced tread width, a buttress portion connecting the tread to the sidewall is designed to have an inclined structure configured by an inclined plane disposed at a large inclination angle from the outside in the tire radial direction toward the inside thereof in order to ensure an enough distance from the belt end portion of the belt reinforcing layer to the buttress surface, so as to prevent the belt end portion from penetrating the buttress portion due to distortion occurring in the belt end portion.